Cluster of Mycobacterium chelonae keratitis cases following laser in-situ keratomileusis

PURPOSE

To describe a cluster of Mycobacterium chelonae keratitis cases involving patients who underwent laser in-situ keratomileusis (LASIK) at a single refractive surgery center.

DESIGN

Descriptive case series of four patients and cohort study to identify disease associations.

METHODS

Examination schedules, diagnostic tests, and therapy were based on best medical judgment. Isolates from three patients were compared by pulsed-field gel electrophoresis. Epidemiologic studies were performed to identify the source of infection.

RESULTS

Seven of eight eyes developed M. chelonae keratitis following bilateral simultaneous LASIK. Each patient was thought to have diffuse lamellar keratitis initially, but all seven eyes were noted to have opacities suggestive of infectious keratitis by 13 to 21 days after surgery. All eyes had undergone hyperopic LASIK over four days in April 2001 by one surgeon in a community-based refractive surgery center. A cohort study of all patients undergoing LASIK at the same center in April 2001 revealed that M. chelonae keratitis occurred only in persons undergoing correction of hyperopia (seven of 14 eyes vs. none of 217 eyes undergoing myopic LASIK, P <.001). The only difference identified between procedures was use of masks created from a soft contact lens in hyperopic LASIK. Three isolates (three patients) were indistinguishable by pulsed-field gel electrophoresis. Eyes were treated with a combination of antimicrobial agents, including topical azithromycin in three patients, with resolution of infection in all eyes over 6 to 14 weeks. The source of infection was not identified on environmental cultures.

CONCLUSION

Postoperative nontuberculous mycobacterial keratitis can occur in an epidemic fashion following LASIK. Topical amikacin, azithromycin, clarithromycin, ciprofloxacin, or a combination of these agents, appears to be effective treatment for these infections.

Experimental staphylococcal endophthalmitis

Endophthalmitis is one of the most feared complications of ocular trauma or surgery. It is a complex pathogen- and host-mediated process that often results in significant vision loss. This review summarizes data from experimental models of staphylococcal endophthalmitis that address the host's immune response to intraocular staphylococci and those that investigate disease pathogenesis.

Acanthamoeba keratitis associated with fungal keratitis

PURPOSE

To report fungal infection complicating Acanthamoeba keratitis.

METHODS

Case report. A 45-year-old woman with contact lens-related bilateral Acanthamoeba keratitis developed corneal ulcer, corneal perforation, and mature cataract in the left eye, which was managed by penetrating keratoplasty, lensectomy, and vitrectomy.

RESULTS

Histopathologic examination of the keratoplasty specimen from the left eye revealed extensive lamellar stromal necrosis with the coexistence of both empty cysts and branching hyphae. Cultures from the keratoplasty specimen grew Scedosporium apiospermum.

CONCLUSION

Keratomycosis caused by S. apiospermum may complicate protracted Acanthamoeba keratitis.

Systemic disorders associated with peripheral corneal ulceration

Peripheral ulcerative keratitis may be associated with a variety of autoimmune diseases. In some diseases, corneal involvement occurs after the systemic disease has been present for many years, whereas in others, it may be the first manifestation. Regardless of the time of presentation, the development of corneal ulceration in the setting of systemic autoimmune disease may represent progression of a potentially life threatening disease. The relatively rare incidence of these diseases has limited publications over the past year to a few case series that have further characterized the natural history of the diseases associated with peripheral ulcerative keratitis. Current laboratory research has been directed at describing the antigenic targets within the cornea of the abnormal immune response in these patients and also the mechanism of keratolysis that results in ulceration.

Penetrating keratoplasty from a temporal approach

PURPOSE

To describe the technique of penetrating keratoplasty using a temporal approach.

METHODS

Report of two cases of phakic penetrating keratoplasty performed with the surgeon positioned at the temporal side of the head.

RESULTS

The temporal approach improved the surgical exposure, which eliminated the need for a bridal suture, facilitated the placement of the first two cardinal sutures, and facilitated subsequent placement of nasal sutures.

CONCLUSION

The temporal approach to penetrating keratoplasty may facilitate suture placement, decrease surgical time, and reduce suture-induced astigmatism.

Adhesion molecule expression in a rat model of Staphylococcus aureus endophthalmitis

PURPOSE

To determine whether Staphylococcus aureus and its components induce expression of E-selectin and intercellular adhesion molecule (ICAM)-1 in rat ocular tissues and on human endothelial cells in culture.

METHODS

Experimental and control rat eyes were injected with 80 colony-forming units of viable S. aureus and lipopolysaccharide-free sterile saline (NS), respectively. Eyes were enucleated and immediately frozen. E-selectin and ICAM-1 expression were evaluated on frozen sections by using standard immunohistochemical techniques. Using an enzyme-linked immunoassay, in vitro expression of E-selectin and ICAM-1 was evaluated on macrovascular endothelial cells after stimulation with S. aureus and selected purified components.

RESULTS

In S. aureus-injected eyes, E-selectin and ICAM-1 expression peaked at six to 24 hours, decreased slightly at 24 and 48 hours, and further declined by 72 hours. However, in NS-injected eyes, peak levels of E-selectin and ICAM-1 were seen at 6 hours, after which expression declined in the areas in which an increase was previously observed. In in vitro assays, peptidoglycan (0.01 microg/ml) induced a fourfold increase in E-selectin (P < 0.0001) and a twofold increase in ICAM-1 (P < 0.002) expression. Ribitol teichoic acid (RTA) (1 microg/ml) induced a twofold increase in E-selectin (P < 0.0001) and a threefold increase in ICAM-1 (P < 0.0001) expression.

CONCLUSIONS

Eyes injected with S. aureus demonstrated a more intense and prolonged expression of both E-selectin and ICAM-1 than did eyes injected with NS. In addition, S. aureus components induced the in vitro expression of these adhesion molecules on macrovascular endothelial cells. The relevance of these findings to microvascular endothelial cells is yet to be determined.

A comparison of the early inflammatory effects of an agr-/sar- versus a wild type strain of Staphylococcus aureus in a rat model of endophthalmitis

PURPOSE

We examined the ability of a wild type and an isogenic mutant strain of Staphylococcus aureus, deficient in the production of hemolysins and lipase (agr (-)/sar (-)), to induce endophthalmitis and inflammatory cell infiltration into the eye at 6, 24 and 48 hours after injection in a rat model of endophthalmitis.

METHODS

Rat eyes were injected with 25 microl of viable S. aureus or sterile saline. Eyes were graded for clinical signs of inflammation daily, removed and processed for standard histologic analysis 6, 24 and 48 hours after injections. Comparisons of clinical scores and mean inflammatory cell numbers were made between S. aureus and control injected eyes.

RESULTS

Both experimental groups developed clinical signs of endophthalmitis and demonstrated infiltration of inflammatory cells at 24 and 48 hours. Clinical inflammation in the Mutant I group was less than the wild type group at these times and significantly less at 48 hours (p<0.05). No statistically significant difference in the number of inflammatory cells was detected between the wild type and Mutant I injected eyes at 24 hours. At 48 hours, inflammatory cells increased by 75.0% in the wild type group and decreased by 19.0% in the Mutant I group and a statistically significant difference was seen between these two groups (p<0.05). At all times, the majority of inflammatory cells were neutrophils. By 48 hours, an increase in monocytes-macrophages was noted.

CONCLUSION

Both strains of S. aureus induced clinical signs of inflammation and inflammatory cell infiltration. Clinical inflammation and inflammatory cell numbers were less in rats injected with the Mutant I strain. These results suggest that hemolysins and lipase may be important in the early induction phase of the inflammatory response.

Cytokine expression in a rat model of Staphylococcus aureus endophthalmitis

PURPOSE

To examine the ability of viable Staphylococcus aureus to induce the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, cytokine-induced neutrophil chemoattractant (CINC), and interferon (IFN)-gamma after intravitreal injection.

METHODS

Experimental rat eyes were injected with a 25-microl volume of approximately 80 colony-forming units of viable S. aureus; control eyes received sterile saline. Eyes were graded daily for signs of clinical inflammation and were removed 6, 24, 48, and 72 hours after injection. One group was prepared for histologic analysis, and vitreous was removed from the other group for cytokine analysis, using standard enzyme-linked immunosorbent assay procedures.

RESULTS

TNF-alpha, IL-1beta, CINC, and IFN-gamma were detected in experimental vitreous samples at increased levels that peaked at 24 hours. TNF-alpha, IL-1beta, and CINC declined at 48 hours, but IFN-gamma remained elevated. At 72 hours, levels returned to baseline. Statistically significant elevations of TNF-alpha, IL-1beta, and CINC were detected in experimental samples at 24, but not at 6 and 48 hours compared with levels in saline control samples (P < 0.03). A statistically significant increase in IFN-gamma was detected at 24 and 48 hours compared with control levels (P < 0.03). In experimental animals, clinical inflammation and inflammatory cells peaked at 24 hours, persisted at 48 hours, and began to decline thereafter. Neutrophils were the predominant inflammatory cell detected at 24 (72.3% of cells) and 48 (60.1%) hours. By 72 hours, the total number of inflammatory cells had decreased by 75.0%, and the cellular infiltrate had changed so that neutrophils equaled monocytes-macrophages.

CONCLUSIONS

S. aureus induced the expression of TNF-alpha, IL-1beta, CINC, and IFN-gamma. The time course of these cytokine levels could account for the clinical inflammatory responses and the entry and decline of vitreous cells in this model of bacterial endophthalmitis.

Timing of dexamethasone treatment in experimental Staphylococcus aureus endophthalmitis

PURPOSE

This study sought to determine whether intravitreal dexamethasone with vancomycin preserves retinal function in eyes with experimental Staphylococcus aureus endophthalmitis better than intravitreal vancomycin alone.

METHODS

Twenty-four rabbits received intravitreal injections in both eyes with S. aureus. Right eyes were treated with intravitreal dexamethasone plus vancomycin and left eyes were treated with vancomycin alone at 24, 36, 48, or 72 hours after inoculation. Evaluation was performed by slit-lamp biomicroscopy, indirect ophthalmoscopy, and electroretinogram. Vitreous humor cultures and histopathologic examinations were performed on the eyes after the rabbits were killed.

RESULTS

The combination of intravitreal dexamethasone and vancomycin resulted in significantly less inflammation than vancomycin alone at 24 and 36 hours after inoculation, but electroretinograms showed significantly better preservation only at 36 hours after bacterial inoculation. Viable bacteria were cultured from eyes treated 48 and 72 hours after inoculation.

CONCLUSION

Intravitreal dexamethasone was found to be beneficial by electroretinography when administered 36 hours after infection. In the authors' model, a single intravitreal injection of vancomycin with or without the addition of dexamethasone was insufficient to sterilize eyes 48 and 72 hours after bacterial inoculation.

Immunopathologic features of Staphylococcus epidermidis-induced endophthalmitis in the rat

PURPOSE

To investigate the clinical, histopathologic and immunologic responses to Staphylococcus epidermidis endophthalmitis in a rat model.

METHODS

Experimental rats received an intravitreal injection of viable S. epidermidis (7000 organisms), while control rats received sterile saline. The clinical scores, cellular infiltrate in vitreous, and levels of serum and vitreous IgM, IgG and IgA to glycerol teichoic acid (GTA), the major antigenic determinant of S. epidermidis cell wall, were all measured from day 1 to day 30 after injection.

RESULTS

The ocular inflammation was largely resolved by day 14. The red reflex was abolished in 50% of rats between days 3 and 10. The bacteria were cleared from the vitreous by day 7. In vitreous, the neutrophils peaked at day 1 and decreased by day 7, and plasma cells were seen between days 1 and 3. Presence of B cells (CD45+/CD3-) was confirmed by flow cytometric analysis of pooled vitreous humor. IgM and IgG but not IgA antibodies to GTA were found in vitreous of injected eyes. The peak of anti-GTA IgM was observed in vitreous of S. epidermidis-infected rats on day 1 and declined by day 7. In contrast to vitreous antibodies, serum anti-GTA IgM antibodies were significantly elevated throughout the course of S. epidermidis endophthalmitis. A weak IgG but no IgA response were observed in serum. Anti-GTA antibodies were also found in low level in normal sera but not in normal vitreous.

CONCLUSIONS

The vitreous antibodies may be involved in neutrophil-mediated opsonophagocytosis leading to 'spontaneous sterility' of the bacteria, and may play a role in the immunopathogenesis of staphylococcal endophthalmitis in the rat.

Determinations of serum tumor necrosis factor alpha in corneal allografts

Corneal allograft rejection culminates in a series of interactions between different classes of antigen presenting cells, cytokines and leukocytes. Tumor necrosis factor-alpha (TNF-alpha) was recently reported to be elevated in acute rejection of solid organ transplants. This cytokine is released early in immune activation and may be detected in the peripheral circulation. Serial determinations of TNF-alpha serum levels were performed following experimental corneal allografts. Lewis rats received 3.5 mm orthotopic corneal grafts of MHC-incompatible Wistar-Furth donors. TNF-alpha concentrations were measured in serum samples collected pre- and postoperatively and measured by micro ELISA. Clinical observations revealed graft rejection in 65.5% of corneal transplants 14 +/- 4 days following grafting. The mean serum level of TNF-alpha in control animals without corneal graft (group I) was 41 +/- 12 pg/ml. Animals following keratoplasty without allograft rejection (group II) showed a mean TNF-alpha level of 54 +/- 16 pg/ml that did not differ from group I. The rejection group III displayed significantly higher TNF-alpha levels (98 +/- 16 pg/ml, p < 0.05). These significantly elevated levels were found even before the diagnosis of rejection was established by clinical criteria. These data suggest systemic immunoreactivity to corneal allografts. Elevated levels of cytokines may provide valuable information in recipients undergoing rejection and may also provide a rationale for systemic immunotherapy in some instances.

Combination intravenous ceftazidime and aminoglycosides in the treatment of pseudomonal scleritis

BACKGROUND

Pseudomonal scleritis is a serious and potentially blinding infection that usually is resistant to medical management.

METHODS

Results for three patients with pseudomonal scleritis who were treated with both topical anti-infectives and a combination of intravenous ceftazidime and aminoglycoside are presented in this case series.

RESULTS

All three patients had a rapid response to the addition of combination intravenous drug therapy to topical therapy; eradication of the infection and healing of the ocular surface occurred within 8 weeks. Only one patient, in whom cystoid macular edema developed, lost useful vision as a result of the infection.

CONCLUSIONS

Combination therapy with intravenous ceftazidime and aminoglycoside may be more effective than single-intravenous agents when used in addition to topical antibiotics and may obviate the need for adjunctive surgical procedures, such ascryotherapy, surgical extirpation, or conjunctival recession.

Air bag-related ocular injuries

This study reviewed the nature and severity of ocular and orbital air bag-related injuries at a large tertiary care referral center. The records of all patients treated by the ophthalmology trauma service for air bag-related ocular injuries between 1993 and 1995 were reviewed. Five patients were identified who had air bag-related ocular trauma. All of the patients who were referred to the ophthalmology trauma service for air bag-related ocular injuries had significant ocular or orbital injury. The extent and severity of the injuries were variable, ranging from orbital contusion to ruptured globe and retinal detachment. Although air bags substantially reduce the overall rates of mortality and morbidity associated with motor vehicle accidents, they also cause a variety of ocular injuries.

Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties

PURPOSE

To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in eyes with concurrent or prior penetrating keratoplasties.

METHODS

Thirty-one eyes of 31 consecutive patients had placement of an Ahmed Glaucoma Valve implant. Median patient age was 65.1 years (range, 17.2 to 103.4 years). The main outcome measure was time after surgery without failure. Success was defined as no additional glaucoma surgeries or devastating visual complications, no new corneal graft failure, an intraocular pressure greater than or equal to 5 mm Hg on the last two follow-up examinations, and reduction in intraocular pressure. For eyes with preoperative intraocular pressure greater than 22 mm Hg, an average intraocular pressure of less than 22 mm Hg on the last two follow-up examinations was required. For eyes with preoperative intraocular pressure of less than 22 mm Hg, an intraocular pressure lowered by at least 20% from preoperative values was required.

RESULTS

Cumulative probabilities of success at 12 and 20 months (mean +/- SD) were 75.4% +/- 8.2% and 51.5% +/- 11.4%, respectively. Eleven of 31 eyes were failures. The risk of failure in eyes with prior infectious keratitis or keratouveitis was estimated to be 5.8 times greater than that associated with eyes that underwent penetrating keratoplasties for other reasons (P = .009).

CONCLUSIONS

Twelve- and 20-month success rates of the implant in eyes with prior or concurrent penetrating keratoplasties were comparable to those of other drainage devices. Eyes with prior infectious keratitis or keratouveitis were at increased risk of failure.

The effect of Staphylococcus aureus phage lysate vaccine on a rabbit model of staphylococcal blepharitis, phlyctenulosis, and catarrhal infiltrates

PURPOSE

To evaluate the effect of Staphylococcus aureus phage lysate (SPL) vaccination on the development of blepharitis, corneal phlyctenules, and catarrhal infiltrates and on the development of antibodies and the delayed-type hypersensitivity response to S. aureus.

METHODS

Eighty rabbits received an intradermal immunization of cell wall-complete Freund's adjuvant followed by a booster immunization. Rabbits were given topical applications of viable S. aureus in both eyes and 40 rabbits received subcutaneous SPL vaccinations. Clinical observations were made weekly. An enzyme-linked immunosorbent assay was used to measure IgG, IgA, and IgM antibody levels to ribitol teichoic acid in sera, corneas, and tears. The delayed-type hypersensitivity response was evaluated by skin testing after subcutaneous injection of staphylococcal antigens.

RESULTS

In the SPL-vaccinated group, phlyctenules developed in eight of 40 rabbits while blepharitis developed in 13 of 40. In the nonvaccinated group, phlyctenules developed in three of 40 rabbits and blepharitis developed in five of 40. The number of rabbits with blepharitis was significantly higher in the SPL-vaccinated group than in the nonvaccinated group. In general, the antibody response to ribitol teichoic acid was enhanced, while the delayed-type hypersensitivity response to S. aureus was depressed.

CONCLUSIONS

Vaccination with SPL was not found to have a beneficial effect on the development of blepharitis, phlyctenules, and catarrhal infiltrates in our rabbit model.

Generation of complement membrane attack complex in normal human corneas

PURPOSE

To determine whether complement-derived SC5b-9, the soluble nonlytic-fluid phase of the membrane attack complex, can be generated in normal human corneas when they are injured with lipopolysaccharide (LPS), ribitol teichoic acid (RTA) immune complexes, acid, or alkali.

METHODS

The experimental cornea of each donor pair was injected with 50 microliters of sterile saline containing 0.5 mg of LPS or 50 microliters of sterile saline containing 250 micrograms of RTA immune complexes. Other experimental corneas were treated topically for 35 seconds with either 200 microliters of 1N HCl or 2N NaOH. The control cornea of each donor pair was injected with 50 microliters of sterile saline or was treated topically for 35 seconds with 200 microliters of sterile saline. After injury, all corneas were incubated in medium 199 for 6 hours at 37 degrees C in 5% CO2, then eluted for 24 hours in phosphate-buffered saline with 10 mM ethylenediaminetetraacetic acid. Each corneal eluate was collected and stored at -70 degrees C until assayed for SC5b-9 by an enzyme immunoassay.

RESULTS

Compared with control corneas, SC5b-9 levels were increased significantly in corneas injected with LPS or RTA immune complexes. However, when compared with controls, SC5b-9 levels were decreased significantly in corneas treated with HCl or NaOH.

CONCLUSIONS

Normal human corneas injured immunologically with LPS or RTA immune complexes activate the classical or alternate pathway and generate SC5b-9. Corneas injured chemically with acid or alkali do not produce SC5b-9.

Corneal scarring after photorefractive keratectomy in a penetrating keratoplasty

PURPOSE

To report severe scarring in a corneal graft after excimer laser photorefractive keratectomy.

METHODS

A 35-year-old man underwent photorefractive keratectomy twice for severe compound myopic astigmatism and anisometropia after penetrating keratoplasty.

RESULTS

Corneal opacity corresponded to areas of irregular epithelial thickness, focal absence of the basement membrane, loss of Bowman's layer, and stromal scarring in the ablation zone.

CONCLUSION

There may be an increased risk of severe corneal stromal scarring from photorefractive keratectomy in eyes that have had previous penetrating keratoplasty.

Complement-derived anaphylatoxins in human donor corneas treated with excimer laser

BACKGROUND AND OBJECTIVE

An inflammatory response produced by excimer laser photorefractive keratectomy (PRK) may be associated with the subsequent corneal haze and regressions in refractive error observed after treatment. Complement-derived anaphylatoxins, potent mediators of inflammation, may have a role in postoperative healing.

MATERIALS AND METHODS

Twenty right human donor corneas underwent a 6-D excimer laser PRK treatment. The corresponding left donor corneas served as the controls. After incubation in tissue culture media for 6 hours and elution in phosphate-buffered saline with EDTA for 24 hours, complement-derived anaphylatoxins C3a, C4a, and C5a were measured in corneal eluates by radioimmunoassay.

RESULTS

Compared with control corneas, the excimer PRK corneas failed to demonstrate a significant increase in C3a, C4a, or C5a levels (P > .05).

CONCLUSIONS

These results suggest that the excimer laser at this dose does not activate significant complement in the cornea.

Immunopathologic features of Staphylococcus aureus endophthalmitis in the rat

PURPOSE

To study the clinical, histopathologic, and immunologic responses to Staphylococcus aureus endophthalmitis in rats.

METHODS

Experimental Lewis rats received an intravitreal injection of viable S. aureus (65 organisms), and control rats received sterile saline. The clinical scores, cellular infiltrate, delayed hypersensitivity reaction in skin tests, and serum and vitreous enzyme-linked immunosorbent assay titers of immunoglobulin (Ig) M, IgG, and IgA to ribitol teichoic acid (RTA), the major antigenic determinant of S. aureus cell wall, were measured and compared on days 3, 7, 10, 14, 21, and 30. The differences were statistically assessed using Mann-Whitney nonparametric t-tests and analysis of variance.

RESULTS

The red reflex was abolished in the majority of rats between days 3 and 21. Ocular inflammation resolved by day 30. The vitreous of eyes injected with S. aureus showed bacterial growth on days 3 and 7, followed by a decrease in numbers on days 10 and 14 and disappearance on days 21 and 30. In the vitreous, a peak neutrophil count was observed at day 3 that rapidly declined by day 7. The number of lymphocytes and plasma cells peaked on day 3 but declined more slowly. Plasma cells and Mott cells were seen on days 10 and 14, suggesting intraocular antibody production. IgM titers to RTA increased progressively in serum and vitreous, reached a peak on day 21, and declined on day 30. A weak IgG but absent IgA response to RTA was observed in serum and vitreous. S. aureus endophthalmitis was not associated with delayed hypersensitivity to the bacteria in skin tests.

CONCLUSIONS

S. aureus endophthalmitis is associated with the infiltration of neutrophils, lymphocytes, monocytes, and plasma cells in vitreous. Neutrophils, the predominant infiltrating cells, may be involved in bactericidal activity and opsonophagocytosis. In rat staphylococcal endophthalmitis, IgM rather than IgG may be the protective antibody.

Effect of topically applied anti-CD4 monoclonal antibodies on orthotopic corneal allografts in a rat model

PURPOSE

Monoclonal antibodies (mAb) have generated interest as therapeutic agents. Limited data are available on the treatment of corneal graft rejection. The purpose of this study was to assess the use of topically applied mAb on experimental corneal grafts.

METHODS

W 3/25, an IgG 1 mouse antirat mAb that recognizes a CD4+ cell subset, was used to treat Lewis recipient rats that received orthotopic corneal grafts of Wistar-Furth donors. Recipients were randomly assigned to receive topically applied drops of liposome-incorporated anti-CD4 mAb (LIP-anti-CD4 mAb), an equivalent amount of free anti-CD4 mAb, an isotype-matched control mAb encapsulated in liposomes (LIP-control mAb), or empty liposomes (emp-LIP) 5 times daily for 10 days. To investigate the immunologic effect of mAb treatment, flow cytometry of the targeted cells and cytotoxic activity of lymphocytes were analyzed.

RESULTS

Application of LIP-anti-CD4 mAb was effective in reducing the rejection rate (P < .05) and in prolonging the mean survival time of corneal grafts that underwent rejection (P < .05). In contrast, no significant effect on graft outcome was observed after the application of control agents. Flow cytometry analysis did not reveal systemic depletion of the targeted lymphocyte subset in any anti-CD4 mAb treated animals. Rejected grafts elicited a cellular cytotoxic immune response in a cell-mediated lymphocytotoxic assay independent of the treatment given.

CONCLUSION

The results suggest that treatment with topically applied LIP-anti-CD4 mAb prolongs graft survival in orthotopic corneal grafts in a rat model. The beneficial effect of LIP-anti-CD4 mAb, probably due to enhanced intraocular delivery, was achieved by using relatively low doses of mAb.

Acanthamoeba sclerokeratitis

We treated a healthy soft contact lens wearer who developed Acanthamoeba sclerokeratitis in the left eye. The patient had severe pain and ring-shaped subepithelial infiltrates. The keratitis progressed and scleral nodules developed despite aggressive treatment with topical clotrimazole, dibromopropamidine isethionate, and corticosteroids. Corneal transplantation and cryotherapy were performed. The corneal button demonstrated Acanthamoeba cysts. Cultures of biopsy specimens taken from two different scleral nodules at two separate times were positive for Acanthamoeba. The disease progressed despite a second corneal graft and the addition of polyhexamethylene biguanide eyedrops. Enucleation of the left eye was required. Histopathologic examination of the specimen documented an Acanthamoeba cyst associated with a granulomatous inflammatory response deep in the sclera. Acanthamoeba scleritis may be associated with a poor prognosis, even with intensive medical and surgical treatment.

Ocular absorption of cyclosporine A from liposomes incorporated into collagen shields

We investigated the ability of liposomes to deliver the immunosuppressive agent cyclosporine A (CsA) to the cornea, anterior sclera, aqueous humor, and vitreous in rabbit eyes. One drop (10 microliters) of liposome-encapsulated CsA (CsA-LIP) or olive oil drops containing an equivalent concentration of CsA (CsA-DR) were administered at 15-minute intervals within the first hour and then one hourly over a 6-hour period. In addition, collagen shields soaked for 30 minutes in the liposome preparation (CsA-LIP-CS) were tested in vitro and in vivo as a new drug delivery approach. CsA levels were measured by fluorescence-immunoassay after 1, 3, or 6 hours of drug administration. CsA levels in this study were highest in cornea and anterior sclera. In animals receiving either CsA-DR or CsA-LIP, CsA levels generally increased from 1 to 6 hours. In animals receiving a single application of CsA-CS-LIP, CsA levels peaked at 3 hours and declined at 6 hours in cornea and sclera. CsA-LIP and CsA-CS-LIP delivered significantly higher levels of CsA to the cornea and sclera at 1 and 3 hours than CsA-DR. In aqueous and vitreous humor, CsA levels increased from 1 to 6 hours in animals receiving either CsA-DR or CsA-LIP. On the other hand, animals receiving a single application of CsA-CS-LIP had lower levels of CsA at 6 hours than at the earlier time points. Animals receiving CsA-LIP or CsA-CS-LIP had significantly higher levels of CsA in aqueous and vitreous humor at 1, 3, and 6 hours than animals receiving CsA-DR.(ABSTRACT TRUNCATED AT 250 WORDS)

Complement system and host defense against staphylococcal endophthalmitis

PURPOSE

The authors studied the role of the complement system in host defense against Staphylococcus epidermidis and S. aureus endophthalmitis.

METHODS

Guinea pigs in the S. epidermidis model received an intravitreal injection of 7000 viable organisms, and guinea pigs in the S. aureus model received 50 viable organisms. The experimental animals in each model were decomplemented with intraperitoneal (IP) injections of cobra venom factor, whereas the control animals received IP injections of normal saline. Mean log bacterial counts in the vitreous and mean serum complement titers were compared in the experimental and control animals in each model on days 1, 2, 3, and 7.

RESULTS

In the S. epidermidis model, mean log bacterial counts in the vitreous were significantly higher in the experimental group than the control group on days 1 and 2 (P < 0.01) and on day 3 (P < 0.05). Mean serum complement titers were significantly lower in the experimental group at all days (P < 0.01). In the S. aureus model, mean log bacterial counts in the vitreous were significantly higher in the experimental group than the control group on day 2 (P < 0.05) and day 3 (P < 0.01). Mean serum complement titers were significantly lower in the experimental group on days 1, 2, and 3 (P < 0.01), but not on day 7.

CONCLUSION

These results suggest that decomplemented guinea pigs show impaired host defense to S. epidermidis and S. aureus endophthalmitis and that this defense is restored as complement levels approach normal.

Collagen shields impregnated with gentamicin-dexamethasone as a potential drug delivery device

We investigated the ability of collagen shields impregnated with gentamicin sulfate and dexamethasone to deliver medication into rabbit eyes. We compared the aqueous humor gentamicin and dexamethasone levels delivered by collagen shield and subconjunctival injection therapy at five time points over a ten-hour period, by using a fluorescence polarization immunoassay and high-pressure liquid chromatography. Our in vitro studies showed that impregnated collagen shields released most of the gentamicin within the first 30 minutes of elution, whereas dexamethasone was released gradually over a ten-hour period. The collagen shields impregnated with gentamicin and dexamethasone produced aqueous gentamicin levels that were significantly lower (P = .014) than those produced by subconjunctival injection therapy at 30 minutes and that were comparable to subconjunctival injection therapy at the other time points. Minimum inhibitory concentrations of gentamicin (approximately 4 micrograms) were observed in aqueous humor within 30 minutes in rabbits that received subconjunctival injections and at one hour in rabbits treated with impregnated collagen shields. The impregnated collagen shields produced aqueous dexamethasone levels that were significantly lower (P = .004) than those produced by subconjunctival injection therapy at one hour, significantly higher (P = .028) than subconjunctival injection therapy at six hours, and comparable to subconjunctival injection therapy at the other time points. Collagen shield delivery of gentamicin-dexamethasone may be comparable to subconjunctival injections and provide an alternative therapy after intraocular surgery.

Ocular absorption of topically applied FK506 from liposomal and oil formulations in the rabbit eye

PURPOSE

To investigate the use of topically applied FK506, a new immunosuppressive compound, systemic and ocular absorption was determined in serum and various ocular tissues.

METHODS

Two drops of 20 microliters FK506 were applied using oil dissolved (OD-FK506) or liposome-bound (LIP-FK506) drug. FK506 concentrations were measured at intervals of 30, 60, and 120 minutes by immunoassay.

RESULTS

After application of OD-FK506, the highest concentrations of FK506 were found in the cornea and the conjunctiva (200-1200 ng/g) with substantial drug also present in anterior and posterior sclera. Relatively low concentrations were measured in the aqueous and vitreous humors (0.2-1.0 ng/g) of these animals. Using the same treatment regimen, LIP-FK506 was effective in delivering significantly higher drug concentrations (P < 0.05) to all ocular tissues and particularly aqueous humor (5-28 ng/g) and vitreous humor (12-22 ng/g) at all time points. During the observation period drug concentrations produced by LIP-FK506 remained well above the therapeutic range. FK506 levels were not detectable in serum (< 0.2 ng/ml) with either drug formulation.

CONCLUSION

These findings indicate that liposomes may be a promising formulation for topical use of FK506 in ocular immune-mediated diseases.

Prolongation of corneal allograft survival with liposome-encapsulated cyclosporine in the rat eye

PURPOSE

To study the effects of different formulations of topical cyclosporine (Cyclosporin A [CsA]) on corneal allograft rejection in a rat model.

METHODS

Female Lewis rats received penetrating keratoplasties from female Wistar-Furth donors. A total of 78 allogeneic grafts were performed. An additional 15 syngeneic grafts (Lewis) were used as technical controls. Two CsA preparations with equivalent drug concentrations (2.1 mg/ml) were applied as drops: CsA encapsulated in large unilamellar liposomes (CsA-LIP) and CsA dissolved in olive oil (CsA-DR). Allogeneic grafts were randomly assigned to receive CsA-LIP or CsA-DR beginning on the day of surgery five times daily for 10 days. Animals without any treatment or receiving empty liposomes (EM-LIP) were used as treatment controls. Grafts were graded three times weekly and a rejection index was generated based on graft clarity, neovascularization, and vessel size.

RESULTS

All syngeneic grafts remained clear over the observation period of 60 days. Rejected allogeneic grafts without any treatment and those receiving EM-LIP or CsA-DR showed a mean survival time (+/- standard deviation) of 14 +/- 4, 14 +/- 5, and 14 +/- 4 days, respectively. There was no significant difference in mean survival time between the grafts without any treatment and those in CsA-DR or EM-LIP treatment groups. The mean survival time of rejected grafts in animals receiving CsA-LIP was prolonged to 20 +/- 4 days. There was a significant difference in the mean survival time between the CsA-LIP treatment group and groups receiving CsA-DR, EM-LIP, or no treatment (P < or = 0.05). The Kaplan-Meier survival curve of the CsA-LIP treatment group was significantly different from the other experimental groups. The graft survival rate in the CsA-LIP group was 77%, whereas the rate was 37% in the non-treated group, 45% in the CsA-DR group, and 36% in the EM-LIP group.

CONCLUSION

Encapsulation of CsA in liposomes might be a promising formulation for use in the prevention of corneal graft rejection.

Immune response to Staphylococcus epidermidis-induced endophthalmitis in a rabbit model

Although Staphylococcus epidermidis is the most common cause of postoperative pseudophakic endophthalmitis, little is known about the immune response to S. epidermidis-induced endophthalmitis. Using a rabbit model, the immune response to an intravitreal injection of 7000 S. epidermidis (group 1) or 30,000 S. epidermidis (group 2) organisms was investigated. Clinical evaluations showed that rabbits in group 2 had a more severe inflammatory reaction in the conjunctiva, cornea, iris, and vitreous than those in group 1. The inflammatory reaction in group 1 largely resolved by day 30; group 2 continued to show a severe inflammatory response. Histopathologic findings correlated with clinical findings, with rabbits in group 2 showing a more severe inflammatory reaction in both the anterior and posterior segments of the globe. Positive vitreous cultures for S. epidermidis were present in rabbits in group 1 on days 3, 7, 10, 14, and 21 but not thereafter. However, group 2 had higher vitreous colony counts at days 3, 7, and 14 and negative vitreous cultures thereafter. Neither group showed delayed hypersensitivity to S. epidermidis antigens (evaluated by skin tests). Serum immunoglobulin (Ig) G antibody levels to phenol-inactivated S. epidermidis and glycerol teichoic acid (GTA) increased progressively, reached a peak at days 10-14, and then declined in both groups. Serum IgA antibody levels to these antigens were not detected. Group 2 had a more prolonged IgG antibody response in vitreous and aqueous than group 1. Tear fluid showed the weakest IgG and IgA antibody response to S. epidermidis and GTA. S. epidermidis-induced endophthalmitis was associated with a humoral but not a delayed hypersensitivity response to this organism.

The effect of systemic decomplementation with cobra venom factor on corneal complement levels in guinea pigs

The authors examined the effect of systemic administration of cobra venom factor (CVF) on hemolytic complement levels in guinea pig sera and corneas. Guinea pigs received repeated intraperitoneal injections of CVF. Sera and corneas were obtained before and 1, 2, 5, 8, 10, 12, 16, and 20 d after the initial injection of CVF. Total hemolytic complement activity was measured by lysis of sheep erythrocytes sensitized with rabbit antibodies. There was a significant decrease in serum complement levels at days 1, 2, 5, 8, and 10 after the initial injection of CVF. After this, complement levels rose to levels that exceeded preinjection values. Complement levels in corneas also declined after CVF injections with a significant decrease at days 2, 5, 8, and 10 and a return to normal thereafter. Corneal complement depletion and restoration lagged behind serum. Moreover, the rate of complement depletion and restoration was greater for serum than cornea. Light microscopic examination of representative corneas at each time did not show local tissue changes during decomplementation. This is first study (to the authors' knowledge) to document corneal complement depletion by systemic administration of CVF. Low-to-absent corneal complement levels were present 2 d after the initial injection of CVF and persisted for 6 d. This model could be used to study the influence of complement on traumatic and immunologic injuries to the cornea.

Use of collagen shields containing amphotericin B in the treatment of experimental Candida albicans-induced keratomycosis in rabbits

We evaluated the effect of collagen shields presoaked with amphotericin B on the treatment of experimental Candida albicans-induced keratitis. Treatment results were compared to those of amphotericin B eyedrops instilled hourly. Forty-eight albino rabbits received intrastromal injections of 10(8) C. albicans organisms. Twenty-four hours later, eyes were treated for eight hours each day with hourly instillation of 0.15% amphotericin B drops, hourly instillation of saline drops, or application of a collagen shield presoaked in 0.5% amphotericin B for one hour. The rabbits were killed after one, three, or five days of treatment. Quantitation of fungi in the cornea was achieved by culturing homogenates and counting colony-forming units. Treatment with amphotericin B applied either as hourly instilled drops or absorbed in collagen shields significantly (P less than .05) reduced corneal fungal counts at all time points when compared to saline-treated control eyes. Rabbit eyes treated with amphotericin B-soaked collagen shields had significantly lower fungal counts compared with hourly instilled amphotericin B drops at Days 1 (P = .02) and 3 (P = .04), but not at Day 5. The collagen shields were as effective in reducing the number of colony-forming units as were amphotericin B drops at Day 5. These data suggest that collagen shields soaked in amphotericin B could be a useful and convenient treatment device in keratomycosis such as that caused by C. albicans.

Conjunctival lymphocytic nodule associated with the Epstein-Barr virus

Infection with Epstein-Barr virus has been reported to have numerous systemic and ocular manifestations. In this study, a 38-year-old man with acute infectious mononucleosis was examined for a painless left red eye of three days' duration. The patient had a two-week history of fatigue, low-grade fever, sore throat, and lymphadenopathy. Serologic evaluation was indicative of an acute primary infection with Epstein-Barr virus. A large, salmon-colored, supranasal bulbar conjunctival mass was observed in the left eye. No associated conjunctivitis was present. Biopsy of the conjunctival lesion disclosed a dense leukocytic infiltrate, which consisted primarily of mature lymphocytes and plasma cells. Immunocytochemical evaluation of the tissue with monoclonal antisera disclosed Epstein-Barr latent membrane protein and nuclear protein 2 in a small fraction of the cells constituting the infiltrate. The conjunctival infiltrate resolved completely within one month, paralleling the regression of the patient's lymphadenopathy.

Scleritis and Streptococcus pneumoniae

We retrospectively review our experience with four patients with Streptococcus pneumoniae scleritis. Two of the patients had been exposed to beta irradiation after pterygium removal 4 and 13 years previously. One patient had a 3-year history of chronic anterior nodular scleritis, and one patient had severe rheumatoid arthritis. All were treated with intensive i.v. and topical fortified antibiotics. In two of the cases, the infection was controlled and visual acuity returned to 20/30 and 20/60. In one patient, infectious scleritis progressed to endophthalmitis. This eye ultimately became phthisical and required enucleation because of chronic pain. In the remaining patient, infectious scleritis led to perforation, which required a corneal-scleral patch graft. This patient had a final visual acuity of counting fingers. An infectious etiology should be suspected in cases of necrotizing scleritis associated with a purulent discharge, and appropriate smears and cultures should be obtained. Infectious scleritis can be caused by streptococcal organisms. Appropriate topical and intravenous antibiotic treatment is effective in some cases.

Antibody studies in a rabbit model of corneal phlyctenulosis and catarrhal infiltrates related to Staphylococcus aureus

Hypersensitivity to ribitol teichoic acid (RTA), the major antigenic determinant of Staphylococcus aureus, may be important in a rabbit model of corneal phlyctenules and catarrhal infiltrates. Over a 5-month period, an enzyme-linked immunosorbent assay was used to measure immunoglobulin (Ig) G and IgA antibody levels to RTA in sera, tears, and corneas from rabbits immunized using the following routes: Group 1, intradermal injections of S. aureus cell wall (CW) mixed with complete Freund's adjuvant (CFA); Group 2, subconjunctival injections of CW-CFA; Group 3, prolonged topical application of viable S. aureus to the eye; Group 4, intradermal injections of CW-CFA plus prolonged topical application of viable S. aureus; and Group 5, subconjunctival injections of CW-CFA plus prolonged topical application of viable S. aureus. Over the 5-month period, the IgG and IgA antibody levels were correlated to RTA with the development of corneal phlyctenules and catarrhal infiltrates. The IgG titers to RTA were higher than IgA titers in serum, tears, and cornea. The highest antibody titers were IgG titers in cornea. Only rabbits immunized by intradermal or subconjunctival injections of CW-CFA followed by prolonged topical application of viable S. aureus (Groups 4 and 5) developed moderate to severe conjunctival hyperemia and edema with corneal phlyctenules and catarrhal infiltrates. When corneal lesions developed between 2-3 months, both groups had the highest corneal IgG and IgA antibody titers to RTA with IgG titers being more than 60 times higher than IgA titers. In the remaining 2 months of the study, the conjunctival response in both groups decreased from moderate-to-severe to mild, and no new corneal lesions developed, despite continued topical application of viable S. aureus and elevated antibody titers in cornea, serum, and tears. In this study, IgG and IgA antibody levels to RTA were measured in serum, tears, and cornea in a rabbit model of corneal phlyctenules and catarrhal infiltrates, and the antibody response was correlated with the development of these hypersensitivity lesions.

Macroscopic pigmentation in a dematiaceous fungal keratitis

The diagnosis of fungal keratitis can be difficult and is often delayed. The distinction between moniliaceous and dematiaceous (pigmented) keratomycoses is not commonly possible on clinical examination. We report a case of a Curvularia lunata fungal keratitis in a 40-year-old patient who presented with diffuse brown pigmentation throughout the ulcer bed. Histologic staining and growth on Sabourad's dextrose agar demonstrated the brown pigmentation characteristic of this pigmented fungus. We call attention to this clinical pigmentation as a helpful clue in the detection of dematiaceous fungal keratitis.

Device drug delivery to the eye. Collagen shields, iontophoresis, and pumps

External devices have been used to enhance drug delivery. This article reviews the role of collagen shields, iontophoresis, and pumps used to deliver ophthalmic medications. Collagen shields have been used to deliver drugs and promote corneal epithelial healing. Presoaked collagen shields deliver many drugs to the eye as well as or better than traditional methods such as frequent topical therapy or subconjunctival injection. The efficacy of drug delivery by collagen shields was demonstrated in animal models of graft rejection and bacterial keratitis. Iontophoresis uses an electrical current to carry an ionized drug across tissue. Transcorneal iontophoresis delivers high concentrations of a drug to the anterior segment of the eye. Transscleral iontophoresis bypasses the lens-iris diaphragm and produces adequate vitreous levels. Pumps deliver fluid to the eye for extended periods of time via a tube with its distal opening in the conjunctival sac, corneal stroma, anterior chamber, or vitreous cavity. Clinical acceptance of the collagen shield for drug delivery to the anterior segment is better than iontophoresis or pumps, probably because the collagen shield is simpler and more convenient to use.

Immune response to Staphylococcus aureus endophthalmitis in a rabbit model

Staphylococcus aureus is an important cause of severe bacterial endophthalmitis. Both immunoglobulin (Ig) G and A antibody titers to ribitol teichoic acid (RTA), the major antigenic determinant of the S. aureus cell wall, were measured by an enzyme-linked immunosorbent assay in serum, tears, aqueous, and vitreous on days 3, 7, 10, 14, 21, and 30 after intravitreal injection of viable S. aureus in rabbits. Clinical examination showed vitreous opacification in all rabbits from days 7-30. Histopathologic examination showed acute inflammation on day 3 and chronic inflammation on days 7-30 in the conjunctiva, cornea, iris, ciliary body, and trabecular meshwork. The vitreous cavity contained neutrophils and necrotic cells on all days. Retinal necrosis was present on days 14-30. Lymphoid follicles with plasma cells were identified in the conjunctiva, ciliary body, and choroid. The vitreous of experimental eyes showed increasing numbers of bacteria from days 3-14, followed by a decrease in numbers on day 21 and absence of viable bacteria on day 30. Increases in IgG antibody levels to RTA were first detected in serum where they were higher than in tears, aqueous, and vitreous until day 14. Vitreous IgG antibody levels to RTA in experimental eyes exceeded all other samples on day 14 and progressively increased thereafter; the other samples declined. The IgA antibody levels were increased in tears on day 14 and in the vitreous of experimental eyes on days 14, 21, and 30. Vitreous IgG antibody levels to RTA were substantially higher than vitreous IgA antibody levels. An inverse correlation was found between vitreous IgG antibody levels and positive vitreous cultures, suggesting that the humoral immune response may be important in the spontaneous sterilization of the vitreous in this model.

Scleral fibroblasts. Human leukocyte antigen expression and complement production

The authors investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to influence production of complement and expression of human leukocyte antigens (HLA) by human scleral fibroblasts in culture. Cell cultures were established by explanting sclera from normal human donor eyes. To study complement production, fibroblasts were treated with 500 units/ml rhIFN-gamma in cell culture, and media were tested for complement components by hemolytic assay after 0, 1, 3, 6, 9, and 11 days. To induce Class II HLAs, fibroblasts were exposed to rhIFN-gamma at concentrations ranging from 10-500 units/ml and incubated for 1, 3, and 6 days. The HLAs were detected by immunofluorescence in conjunction with flow cytometry. Class I antigen was detected using a monoclonal antibody directed against beta 2-microglobulin. Class II histocompatibility antigens were identified using monoclonal antibodies specific for HLA-DR, -DP, and -DQ. Although complement component C1 was produced constitutively in cell culture, the addition of rhIFN-gamma resulted in an increase in production. Complement components C2 and C4 were detected only after treatment with rhIFN-gamma. Complement production was completely inhibited by cycloheximide, and C3, C5, C6, and C7 were not present in cell culture media with or without rhIFN-gamma. Class I antigen was present on all cells before induction, and an increase in expression was noted after exposure to rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, scleral fibroblasts expressed HLA-DR, -DP, and -DQ in a dose-dependent, time-related fashion. These findings suggest that rhIFN-gamma has multiple effects on scleral fibroblasts: (1) increased production of C1, (2) production of C2 and C4, (3) up-regulation of Class I antigen expression, and (4) expression of Class II antigens. They also suggest that scleral fibroblasts have the potential to participate in immunologic diseases of the eye.

Successful medical management of Acanthamoeba keratitis

Seven patients with documented Acanthamoeba keratitis were treated with prolonged and intensive triple antiamoebic therapy consisting of topical neomycin-polymyxin B-gramicidin, propamidine isethionate 0.1%, and miconazole nitrate 1%. Additionally, five patients were treated with topical corticosteroids. Six of seven patients were cured of Acanthamoeba keratitis with medical therapy alone, one patient required therapeutic penetrating keratoplasty to eradicate the infection. Two patients underwent penetrating keratoplasty to improve their vision after medical therapy. Our series differs from previous reports in that triple antiamoebic therapy was used in all seven patients and was successful in both early and advanced cases of Acanthamoeba keratitis. Prolonged and intensive topical therapy with these three antiamoebic drugs may be an effective mode of therapy for Acanthamoeba keratitis.

Generation of complement-derived anaphylatoxins in normal human donor corneas

Complement-derived anaphylatoxins (C3a, C4a, and C5a) are potent, stable mediators of acute inflammation. Because human corneas contain functional complement, the authors subjected normal human donor corneas to various forms of immunologic or chemical injury to determine if the complement system could be activated and anaphylatoxins generated. The experimental cornea of each donor pair was injected with lipopolysaccharide (LPS) or immune complexes or injured by application of acid or alkali. The remaining cornea of each donor pair served as a control. After incubation of corneas in tissue culture media for 6 hours and elution in phosphate-buffered saline for 24 hours, C3a, C4a, and C5a were measured in corneal eluates by radioimmunoassay. Compared with control corneas, C3a levels were significantly increased in corneas injected with LPS or immune complexes and in corneas injured with acid or alkali. C4a levels were significantly elevated in corneas injected with immune complexes and in corneas injured with acid or alkali but not in corneas injected with LPS. C5a levels were detectable only in corneas injured with acid or alkali. These results suggest that immunologic reactions in the human cornea may activate the classic or alternative complement pathways and generate anaphylatoxins. Additionally, chemical injuries with acid or alkali generate anaphylatoxins in the cornea. Anaphylatoxins may participate in the acute inflammatory response of the human cornea to chemical or immunologic injury.

Giant papillary conjunctivitis associated with elevated corneal deposits

A patient presented with central corneal scarring and neovascularization associated with elevated deposits that were shown to be keratin and calcium. Giant papillary conjunctivitis (GPC) was noted at a corresponding location in the palpebral conjunctiva. The lid reaction resolved after the elevated corneal deposits were debrided. A rigid gas-permeable contact lens was then fitted for visual rehabilitation. Either foreign bodies or elevated corneal deposits may cause GPC.

Ocular trauma caused by exploding glass bottles containing dry ice and water

We treated three patients with severe ocular injuries caused by exploding glass bottles containing a mixture of dry ice chips and water. One patient had a corneal laceration and traumatic cataract with several retained intraocular glass fragments. The second had a scleral laceration without corneal or lenticular involvement. The third suffered a corneal-scleral laceration, with a total retinal detachment. Following surgery, two patients recovered 20/20 vision; the third patient regained only light perception.

Cicatricial pemphigoid and erythema multiforme

Cicatricial pemphigoid (CP) and erythema multiforme (EM) are bullous diseases that involve the skin and mucous membranes including the conjunctiva. Of all the bullous diseases, CP and EM not only involve the conjunctiva most frequently but also cause the most severe conjunctival disease. A chronic, progressive disease, CP is characterized by shrinkage of the conjunctiva, symblepharon, entropion, trichiasis, dry eye, and finally reduced vision from corneal opacification. It is primarily a disease of the elderly that affects more women than men and is characterized by blisters or bullae in a subepithelial location and immunoglobulins and complement bound to the basement membrane zone of skin and mucous membranes including the conjunctiva. Circulating antibodies to the basement membrane zone can be demonstrated occasionally. Treatment includes artificial tears, topical antibiotics, correction of entropion and trichiasis, therapeutic soft contact lenses, and systemic immunosuppressive therapy including corticosteroids. An acute, generally self-limited, inflammatory disorder of the skin and mucous membranes, EM occurs primarily in young, healthy individuals. The most frequent precipitating factors are (1) drugs and (2) infections caused by Mycoplasma pneumoniae and herpes simplex. Conjunctival involvement ranges from a mild catarrhal conjunctivitis which terminates without sequelae to membranous conjunctivitis which may heal leaving scarring, symblepharon, and even ankyloblepharon. Histopathologic findings include subepithelial bullae and perivascular mononuclear cell infiltrates. Patients with EM have circulating immune complexes and immunoreactant deposition in the blood vessel walls of the dermis. After the acute episode has subsided, they may require artificial tears, topical antibiotics, correction of entropion and trichiasis, therapeutic soft contact lenses, tarsorrhaphy, and mucous membrane grafts.

Collagen shield delivery of amphotericin B

By using a high-pressure liquid chromatography assay, we investigated the ability of collagen shield therapeutic contact lenses to release amphotericin B and deliver it to the anterior segment of rabbit eyes. In vitro studies showed that presoaked collagen shields released most of the amphotericin B within the first hour of elution. We compared the corneal and aqueous humor amphotericin B levels produced by collagen shields soaked in amphotericin B and frequent-drop therapy at four time points over a six-hour period. The collagen shields soaked in amphotericin B produced corneal levels that were higher than those produced by frequent-drop therapy at one hour, equivalent to drop therapy at two and three hours, and lower than drop therapy at six hours. There were no differences in amphotericin B levels in aqueous humor at any time point between rabbits treated with collagen shield delivery and rabbits treated with frequent-drop delivery. The results of this study suggest that amphotericin B delivery to the cornea by collagen shields is comparable to frequent-drop delivery but has the potential benefit of added convenience and compliance.

Inflammatory mediators in the vitreous humor of AIDS patients with retinitis

We measured levels of protein, of complement-derived anaphylatoxins (C3a, C4a, and C5a), and of the lymphokines interleukin-2 and gamma interferon, in vitreous humor from 10 AIDS patients with vitritis and retinitis (group 1). We compared these measurements with levels in vitreous from 7 patients with vitritis but without AIDS (group 2), 10 patients with vitreous hemorrhages (group 3), and 20 patients with retinal detachments or epiretinal membranes without clinical evidence of vitreal inflammation (group 4). Vitreous humor from 10 AIDS patients had measurable levels of interleukin-2 in three of nine samples, gamma interferon in six of nine samples, C3a and C4a in all ten samples, and C5a in only one of ten samples. Vitreous humor from group 1 did not differ significantly from vitreous from group 2. On the other hand, vitreous from group 1 had significantly higher levels of gamma interferon, C3a, and C4a, and higher ratios of these anaphylatoxins to protein, in comparison to vitreous in groups 3 and 4. The results of this study suggest that vitreous humor from AIDS patients with retinitis contains activated complement and may contain interleukin-2 and gamma interferon. Viral retinitis is associated with the presence of lymphokines in vitreous humor. Additionally, anaphylatoxin and gamma interferon levels, but not interleukin-2 levels, correlate with vitreal inflammation. This is the first study to measure interleukin-2, gamma interferon, and C5a levels in human vitreous humor.

Is daily wear better than extended wear? Arguments in favor of daily wear

The use of contact lenses for extended wear appears to be accompanied by an increase in several complications, the most serious of which is corneal infection. It has been proposed that infection is due to corneal epithelial layer microtrauma and lens care system contamination, but noncompliance, contamination of care systems, and microtrauma [especially among keratoconics and polymethylmethacrylate (PMMA) lens users, for example] are so common in daily wear that we believe they are insufficient to explain the approximately sixfold increase in the rate of corneal infection with extended wear. Perhaps the chronic hypoxic stress of extended wear use of contact lenses substantially reduces the resistance of the epithelium to either injury or microbial infection. Until evidence is provided that new contact lenses have sufficient oxygen transmissibility (Dk/L) to fully satisfy corneal oxygen needs under extended wear conditions, and the extended wear use of such lenses is thoroughly tested in a study population, we believe that the majority of contact lens patients should be maintained on daily wear schedules.

Modulation of HLA antigen expression on conjunctival fibroblasts by gamma-interferon

We investigated the ability of recombinant human gamma-interferon (rhIFN-gamma) to induce class II HLA antigen expression on human conjunctival fibroblasts in cell culture. Cultures were established by explanting subconjunctival tissue from normal donor globes. Fibroblasts were treated with rhIFN-gamma at concentrations ranging from 1 to 500 units/ml and incubated for 1, 3 and 6 days. HLA antigens were detected by immunofluorescence using monoclonal antibodies in conjunction with flow cytometry. Class I antigen was identified using a monoclonal antibody directed against Beta-2 microglobulin (a component of the class I antigen complex). Class II histocompatibility antigens were detected using monoclonal antibodies specific for HLA-DR, HLA-DP and HLA-DQ. Class I antigen was present on all cells prior to induction and showed a trend toward increased density after treatment with rhIFN-gamma. Class II antigens were absent before induction with rhIFN-gamma. After treatment with rhIFN-gamma, class II antigens were induced in a dose- and time-dependent fashion. HLA-DR expression was most sensitive to induction by rhIFN-gamma, followed by HLA-DP, and then HLA-DQ. The up-regulation of HLA class I antigen expression and the inducible expression of class II antigens following exposure to rhIFN-gamma suggest that conjunctival fibroblasts have the potential to participate in immunologic diseases of the external eye.

Distribution of complement in the sclera

In the present study, we compared hemolytic activities of C1, C4, C2, C3, C5, C6 and C7 in the anterior and posterior sclera. Additionally, we used radial immunodiffusion to measure levels of Factor B, IgG, IgA and albumin in the anterior and posterior sclera. Except for C1, complement levels were significantly higher in the posterior than anterior sclera. Additionally, levels of immunoglobulins as well as albumin were significantly higher in the posterior than anterior sclera. These results suggest that the posterior sclera has a better adjacent vascular supply than the anterior sclera. On the other hand, the results of this study show that the anterior sclera has more C1, the recognition unit of the classical pathway, than the posterior sclera. Because there is nearly twice as much C1 in the anterior sclera, it may be easier for antigen-antibody complexes, whether formed in the sclera itself or derived from the neighboring vessels, to set off the complement cascade in the anterior sclera. This finding may help explain why scleritis associated with immune complex disease is more common in the anterior than posterior sclera.